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Abstract:

A guidewire comprising an elongate guide member dimensioned for insertion
within a body vessel of a subject is disclosed. The guide member defines
a longitudinal axis and has trailing and leading end segments. The
leading end segment has a reduced cross-sectional dimension relative to a
cross-sectional dimension of the trailing end segment. The leading end
segment includes at least one finger thereon. A first transverse
dimension of the finger is greater than a corresponding first transverse
dimension of the leading end segment in contact therewith.

Claims:

1. A guidewire comprising: an elongate guide member defining a
longitudinal axis and having trailing and leading end segments, the
leading end segment dimensioned for positioning within a body vessel, the
leading end segment including a remote segment having a reduced
cross-sectional dimension relative to a cross-sectional dimension of the
trailing end segment, the remote segment including a pair of lateral
sides extending along the longitudinal axis; and at least two fingers
disposed on the remote segment, adjacent fingers being axially spaced
relative to the longitudinal axis to define a predetermined distance
therebetween, a first transverse dimension of each of the at least two
fingers being greater than a corresponding first transverse dimension of
the remote segment in contact therewith such that each of the at least
two fingers project laterally beyond both of the lateral sides of the
remote segment, the at least two fingers each defining a longitudinal
dimension along the longitudinal axis less than the predetermined
distance between the at least two fingers.

2. (canceled)

3. The guidewire according to claim 1 wherein the at least two fingers
include different first transverse dimensions.

4. The guidewire according to claim 1 wherein a second transverse
dimension of each of the at least two fingers is substantially equal to a
corresponding second transverse dimension of the remote segment.

5. The guidewire according to claim 1 wherein the leading end segment and
the at least two fingers are made of the same material.

6. The guidewire according to claim 1 wherein the first transverse
dimension of each finger of the at least two fingers along the first
transverse axis is between about 0.002 inches and about 0.004 inches.

7. The guidewire according to claim 6 wherein the first transverse
dimension of the remote segment along the first transverse axis is
between about 0.001 inches and about 0.002 inches.

8. The guidewire according to claim 7 wherein a second transverse
dimension of each finger of the at least two fingers along a second
transverse axis is between about 0.003 inches and about 0.005 inches.

9. The guidewire according to claim 6 wherein the predetermined distance
between the at least two fingers is between about 0.010 inches and about
0.030 inches.

10. The guidewire according to claim 1 wherein the ratio between the
first transverse dimension of each of the at least two fingers along the
first transverse axis and the first transverse dimension of the remote
segment along the first transverse axis is about 2:1.

11. The guidewire according to claim 1 wherein the at least two fingers
are each dimensioned to extend through a radial center of the leading end
segment.

12. The guidewire according to claim 1 wherein the remote segment defines
a polygonal cross-section.

13. The guidewire according to claim 12 wherein the at least two fingers
each define a polygonal cross-section.

14. The guidewire according to claim 1 wherein a distal-most end of the
distal-most finger is positioned proximally of a distal-most end of the
remote segment.

15. (canceled)

16. The guidewire according to claim 1 wherein the leading end segment
and the at least two fingers are monolithically formed.

17. The guidewire according to claim 1 further comprising an intermediate
segment positioned between the remote segment and the trailing end
segment, the intermediate segment having a cross-sectional dimension that
is larger than the cross-sectional dimension of the remote segment and
that is smaller than the cross-sectional dimension of the trailing end
segment.

18. A method for manufacturing a guidewire dimensioned for insertion
within a body vessel of a subject, the method comprising: forming a guide
member defining a longitudinal axis and having trailing and leading end
segments, the leading end segment including a remote segment having a
reduced cross-sectional dimension relative to a cross-sectional dimension
of the trailing end segment, the remote segment including a plurality of
fingers, adjacent fingers being disposed in axial spaced relation at a
predetermined axial distance, a first transverse dimension of each finger
being greater than a corresponding first transverse dimension of the
remote segment in contact therewith, each finger defining a longitudinal
dimension along the longitudinal axis less than the predetermined
distance between the adjacent fingers; and at least one coil mounted
about at least the remote segment.

19. The method of claim 18 wherein the step of forming includes stamping
the remote segment and the at least one finger.

20. The method of claim 18 wherein the step of forming includes micro
machining the remote segment and the at least one finger.

21. The guidewire according to claim 13 wherein the at least two fingers
each define a general rectangular cross-section transverse to the
longitudinal axis.

22. The guidewire according to claim 18 wherein each finger define a
general rectangular cross-section transverse to the longitudinal axis.

23. A medical guidewire comprising: an elongate guide member defining a
longitudinal axis and having proximal and distal end segments, the distal
end segment including a reduced cross-sectional dimension relative to a
cross-sectional dimension of the proximal end segment, the distal segment
dimensioned for positioning within a body lumen; and at least three
fingers disposed along the distal end segment, adjacent fingers being
spaced along the longitudinal axis to define a predetermined distance
therebetween, each finger defining first and second transverse
dimensions, the first transverse dimension of each finger being greater
than a corresponding first transverse dimension of the distal end segment
in contact therewith such that each finger extends beyond lateral edges
of the distal end segment, each finger defining a longitudinal dimension
along the longitudinal axis less than the predetermined distance between
adjacent fingers.

24. The guidewire according to claim 23 wherein adjacent fingers of the
at least three fingers are axially spaced along the longitudinal axis at
the same distance.

25. The guidewire according to claim 23 wherein adjacent fingers of the
at least three fingers are axially spaced along the longitudinal axis at
different distances.

26. The guidewire according to claim 23 wherein the at least fingers
define a general rectangular shape in plan view.

27. The guidewire according to claim 23 wherein the distal end segment
defines a distal tip, and the at least three fingers includes a
distalmost finger, the distalmost finger being proximally spaced from the
distal tip.

28. The guidewire according to claim 27 including at least one coil
coaxially mounted about the leading end segment.

29. The guidewire according to claim 28 including an outer sheath
enclosing the at least one coil.

30. The guidewire according to claim 23 wherein each finger defines a
first transverse dimension greater than a second transverse dimension.

31. The guidewire according to claim 30 wherein each finger and the
distal end segment each define a general rectangular cross-section
transverse to the longitudinal axis.

Description:

BACKGROUND

[0001] 1. Technical Field

[0002] The present disclosure generally relates to medical devices, and,
in particular, relates to an intravascular guidewire for assisting in
placement of an intravascular device within the neurovasculature for
facilitating diagnostic and/or therapeutic neurovascular procedures.

[0003] 2. Description of Related Art

[0004] Guidewires are commonly used in medical procedures to assist in the
advance and proper positioning of a catheter or other medical device in
lumens, vessels, or other cavities of the body. Neurovascular procedures
utilizing guidewires include the imaging and treatment of aneurysms,
arteriovenous malformations (AVM), and ischemic stroke. The effectiveness
of an intravascular guidewire in advancing through tortuous
neurovasculature without undesired deformation or kinking is dependent
upon a number of factors and design considerations. These factors
include, inter alia, the material(s) of fabrication of the guidewire,
guidewire dimensions and intended use. Generally, a balance must be
achieved to provide the required torsional, lateral, tensile and/or
column strengths to enable easy and precise manipulation and steerability
in the tortuous vasculature. Guidewires for such endovascular procedures
face additional challenges due to the relatively small diameter required
to navigate through the narrow and remote locations of the
neurovasculature.

SUMMARY

[0005] Accordingly, the present disclosure is directed to a guidewire
capable of accessing distal reaches of the vasculature, including the
neurovasculature, while exhibiting sufficient torsional and lateral
stiffness to enable steering of the guidewire through these tortuous
regions. What is also desired is a guidewire having a distal end with
improved tensile and torsional integrity, yet with the capability to
readily bend in any direction.

[0006] In accordance with one embodiment of the present disclosure, a
guidewire comprising an elongate guide member dimensioned for insertion
within a body vessel of a subject. The guide member defines a
longitudinal axis and has trailing and leading end segments. The leading
end segment has a reduced cross-sectional dimension relative to a
cross-sectional dimension of the trailing end segment. The leading end
segment includes at least one finger thereon. A first transverse
dimension of the finger is greater than a corresponding first transverse
dimension of the leading end segment in contact therewith.

[0007] In disclosed embodiments, the leading end segment includes at least
two fingers axially spaced along the leading end.

[0008] In disclosed embodiments, the two fingers include a different
transverse dimension from each other.

[0009] In disclosed embodiments, a second transverse dimension of the at
least one finger is substantially equal to a corresponding second
transverse dimension of the leading end segment.

[0010] In disclosed embodiments, the leading end segment and the fingers
are made of the same material.

[0011] In disclosed embodiments, a length of each finger along the first
transverse axis is between about 0.002 inches and about 0.004 inches.
Here, it is disclosed that a width of the leading end segment along the
first transverse axis is between about 0.001 inches and about 0.002
inches. It is further disclosed that the width of each finger along the
second transverse axis is between about 0.003 inches and about 0.025
inches. The leading end segment may include at least two fingers axially
spaced along the leading end and the distance between adjacent fingers
may be between about 0.010 inches and about 0.100 inches.

[0012] In disclosed embodiments, the ratio between a length of the finger
along the first transverse axis and a width of the leading end segment
along the first transverse axis is about 2:1.

[0013] In disclosed embodiments, the at least one finger extends through a
radial center of the leading end segment. It is further disclosed that
the leading end segment and/or at least one finger may define a polygonal
cross-section.

[0014] In disclosed embodiments, a distal-most end of the distal-most
finger is positioned proximally of a distal-most end of the leading end
segment.

[0015] In disclosed embodiments, the leading end segment includes a pair
of lateral sides disposed parallel to the longitudinal axis, and at least
one finger projects laterally beyond each of the lateral sides of the
leading end segment.

[0016] In disclosed embodiments, the leading end segment and the fingers
are monolithically formed.

[0017] In disclosed embodiments, the guidewire further comprises an
intermediate segment positioned between the leading end segment and the
trailing end segment. The intermediate segment has a cross-sectional
dimension that is larger than the cross-sectional dimension of the
leading end segment and that is smaller than the cross-sectional
dimension of the trailing end segment.

[0018] In accordance with another embodiment of the present disclosure, a
method for manufacturing a surgical guidewire dimensioned for insertion
within a body vessel of a subject is disclosed. The method comprises
forming a guide member defining a longitudinal axis and having trailing
and leading end segments. The leading end segment includes a reduced
cross-sectional dimension relative to a cross-sectional dimension of the
trailing end segment. The leading end segment includes at least one
finger thereon. A first transverse dimension of the at least one finger
is greater than a corresponding first transverse dimension of the leading
end segment in contact therewith.

[0019] In disclosed embodiments, the leading end segment and the at least
one finger are formed via micro machining or via stamping.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the present disclosure will be readily appreciated
by reference to the drawings wherein:

[0021] FIG. 1 is a perspective view of a guidewire and catheter in use
within a tortuous region of the vasculature of a patient in accordance
with the principles of the present disclosure;

[0022] FIG. 2 is a perspective view with parts separated of the guidewire
of FIG. 1 illustrating the guide member, support coils and outer sheath;

[0023] FIG. 3 is a perspective view of a portion of a leading end segment
of the guide member of the guidewire of FIGS. 1 and 2;

[0024] FIG. 4 is a plan view of a portion of the leading end segment of
the guide member of the guidewire of FIGS. 1-3;

[0025] FIG. 5 is an elevation view of a portion of the leading end segment
of the guide member of the guidewire of FIGS. 1-4; and

[0026] FIG. 6 is a longitudinal cross-sectional view of the guidewire of
FIG. 2;

[0027] FIG. 7 is a transverse cross-sectional view of the guidewire of
FIG. 6 taken along line 7-7;

[0028] FIG. 8 is a transverse cross-sectional view of the guidewire of
FIG. 6 taken along line 8-8;

[0029] FIG. 9 is a transverse cross-sectional view of the guidewire of
FIG. 6 taken along line 9-9; and

[0030] FIGS. 10-12 are perspective views of the leading end segment of the
guide member according to embodiments of the present disclosure.

DESCRIPTION

[0031] In the following description, the terms "proximal" and "distal" as
used herein refer to the relative position of the guidewire in a lumen.
The "proximal" or "trailing" end of the guidewire is the guidewire
segment extending outside the body closest to the clinician. The "distal"
or "leading" end of the guidewire is the guidewire segment placed
farthest into a body lumen from the entrance site.

[0032] The guidewire of the present disclosure has particular application
in a neurovascular procedure, but may be used in any interventional,
diagnostic, and/or therapeutic procedure including coronary vascular,
peripheral vascular, and gastro-intestinal applications in addition to a
neurovascular application.

[0033] In the figures below, the full length of the guidewire is not
shown. The length of the guidewire can vary depending on the type of
interventional procedure, though typically it ranges in length from 30
centimeters to 400 centimeters (cm). Common lengths of guidewires for
coronary, peripheral and neurovascular procedures may range from 170 cm
to 300 cm in length. These lengths permit the use of standardized rapid
exchange or over-the-wire catheter systems. The length of the shaped
distal end also may vary, for example, from about 5 cm to about 80 cm in
length.

[0034] In accordance with one application of the present disclosure, the
maximum outer diameter of the guidewire ranges from about 0.008 inches to
about 0.035 inches, standard for guidewires used in a neurovascular
procedure. The diameter of the guidewire may remain relatively constant
over a major portion of the length of the guidewire; however, the leading
or distal end incorporates a generally tapered or narrowed configuration
to permit flexure while navigating the tortuous vasculature.

[0035] The various embodiments of the disclosure will now be described in
connection with the figures. It should be understood that for purposes of
better describing the disclosure, the figures may not be to scale.
Further, some of the figures include enlarged or distorted portions for
the purpose of showing features that would not otherwise be apparent.

[0036] Referring now to FIG. 1, a tortuous vasculature such as within the
neurovascular space "n" is illustrated. For illustrative purposes, a
tortuous path or a tortuous region within, e.g., the neurovascular space
"n," includes large vasculature "V1" and smaller branch vessels
"V2" which branch or extend from more proximal vessels at various
angles, including up to 90 degrees or even greater than 90 degrees.

[0037] In FIG. 1, guidewire 10 of the present disclosure is illustrated as
being positioned within a conventional access or microcatheter 100. Such
microcatheters are known in the art. Commercially available
microcatheters include Echelon®, Marathon®, and Nautica®
microcatheters sold by Tyco Healthcare Group LP dba Covidien, Irvine,
Calif. In general, microcatheter 100 includes handle 102 and hollow
catheter member 104 extending from the handle 102. Microcatheter 100
defines a longitudinal opening extending at least through catheter member
104 for passage or reception of guidewire 10.

[0038] Guidewire 10 includes actuator 12 and guide member 14 extending
from the actuator 12. Actuator 12 may incorporate various features
including handles, slides or the like, to facilitate handling and/or
movement of guide member 14. For example, actuator 12 may be used to
translate and/or rotate guide member 14 during placement within the
vasculature.

[0039] Referring now to FIG. 2, guide member 14 of guidewire 10 is
illustrated and will be discussed in greater detail. Guide member 14 is
dimensioned for insertion within the vasculature. Guide member 14 defines
longitudinal axis "A" and has proximal or trailing end segment 16, and
distal or leading end segment 18 forward of the trailing end segment 16.
In FIG. 2, a major longitudinal portion of proximal end segment 16 is
removed for ease of illustration. Trailing end segment 16 may be
generally circular in cross-section with a length ranging from about 20
cm to about 240 cm, for example. Trailing end segment 16 may have a
constant cross-sectional dimension or diameter along its length.

[0040] With reference now to FIGS. 2-3, leading end segment 18 of guide
member 14 forms the working end or tip of the guidewire 10 and defines a
reduced cross-sectional dimension relative to the cross-sectional
dimension of proximal end segment 16. The overall length "L" (FIG. 2) of
leading end segment 18 may range from about 20 cm to about 60 cm
depending on the maximum diameter (e.g., the diameter of proximal end
segment 16) and the overall length of guidewire 10. Leading end segment
18 may include a number of alternating tapered and annular segments which
generally increase in cross-sectional dimension or diameter from the
extreme remote or distal end toward the proximal end, i.e., toward
proximal end segment 16. In the embodiment of FIGS. 2-3, leading end
segment 18 includes a distal remote segment 20, a first tapered segment
22 extending proximally from distal remote segment 20 and coterminous
therewith, a first generally annular segment 24 extending from the first
tapered segment 22 and coterminous therewith, a second tapered segment 26
extending from the first generally annular segment 24 and coterminous
therewith, and a second generally annular segment 28 extending from the
second tapered segment 26 and being coterminous therewith. Leading end
segment 18 may further include a third tapered segment 30 extending
contiguously from second annular segment 28 and a third annular segment
32 which is coterminous with the third tapered segment 30. As a further
alternative, leading end segment 18 may also include a fourth tapered
segment 34 extending from third annular segment 32 to leading end segment
16. First, second and third annular segments 24, 28, 32 may define
circular cross-sections with various diameters as depicted in the
cross-sectional views of FIGS. 7, 8 and 9, respectively. Suitable
diameters of each of annular first second and third annular segments 24,
28, 32 for specific guidewire sizes will be provided hereinbelow. Tapered
segments 22, 26, 30 and 34 are in oblique relation to the longitudinal
axis "A." Tapered segments 22, 26 may define an angle relative to
longitudinal axis "A" ranging from about 5 degrees to about 30 degrees.
Tapered segments 30, 34 may define a greater angle relative to
longitudinal axis "A," e.g., ranging from about 20 degrees to about 70
degrees.

[0041] While the present disclosure identifies several remote segments 20,
20a, 20b, and 20c, reference number 20 is intended to include each remote
segment 20, 20a, 20b, and 20c. Additionally, while the present disclosure
identifies several variations of fingers 21, 21a, 21b and 21c, reference
number 21 is intended to include each variation of finger 21.

[0042] Remote segment 20 may define various configurations. In the
embodiment of FIGS. 2-6 and 10-12, remote segment 20 is a flattened,
planar or ribbon tip. However, remote segment 20 may define alternative
cross-sectional shapes including circular, oval or the like. As a further
alternative, remote segment 20 may be heat set into a variety of
configurations including a linear arrangement. In one embodiment, remote
segment 20 is heat set to maintain, e.g., a non-linear configuration such
as a curve, by subjecting the remote segment 20 to heat at about
500° C. to about 525° C. for a duration of time ranging
from about 30 seconds to about 2 minutes. Remote segment 20 may also be
provided with a bent "j-hook" as is known in the art, or, may be bent
into a "j-hook" design by the clinician prior to the interventional
procedure.

[0043] With particular reference to FIGS. 3-5 and 10-12, remote segment 20
is shown including a plurality of fingers 21. It is envisioned that the
inclusion of fingers 21 on remote segment 20 helps transmit torque
applied by actuator 12 to leading end segment 18, without significantly
impacting the flexibility of leading end segment 18.

[0044] In the embodiment illustrated in FIGS. 3-5, leading end segment 18
of guide member 14 includes a plurality of fingers 21 thereon. Each
finger 21 defines a first transverse dimension "FB" along a first
transverse axis "B" (i.e., transverse to longitudinal axis "A"), a second
transverse dimension "FC" along a second transverse axis "C" (i.e.,
transverse to longitudinal axis "A" and perpendicular to longitudinal
axis "B"), and a longitudinal dimension "FA" along the longitudinal
axis "A." Additionally, leading end segment 18 defines a first transverse
dimension "SB" along the first transverse axis "B," and a second
transverse dimension "SC" along the second transverse axis "C."

[0045] In the embodiment illustrated in FIGS. 3-5, remote segment 20 of
leading end segment 18 includes three fingers 21, which are all
identically sized, shaped and axially spaced apart from adjacent fingers
21. The present disclosure also contemplates more or fewer than three
fingers 21 (e.g., two fingers as shown in FIGS. 11 and 12), and fingers
21 that differ in size, shape and/or spacing from adjacent fingers 21.
Additionally, while fingers 21 are shown extending through a radial
center of remote segment 20 of leading end segment 18, at least one
finger 21 may extend along an upper surface 19a or a lower surface 19b of
remote segment 20.

[0046] Additionally, and as particularly shown in FIGS. 2-4 and 6, first
transverse dimension "FB" of finger 21 is greater than the
corresponding first transverse dimension "SB" of remote segment 20
of leading end segment 18 (i.e., the portion of leading end segment 20
that finger 21 is in contact with). In disclosed embodiments, the
distance "FB" is between about 0.002 inches and about 0.004 inches,
for example. It is also disclosed that the distance "SB" is between
about 0.001 inches and about 0.002 inches. Further, it is envisioned that
the ratio between "FB" and "SB" is about 2:1. In disclosed
embodiments, the distance "FA" is between about 0.003 inches and
about 0.025 inches, and the distances "FC" and "SC" are between
about 0.001 inches and about 0.005 inches. Further, it is envisioned that
the distances "FC" and "SC" are equal to one another. It is
further disclosed that a distance "AFA" between adjacent fingers 21
is between about 0.010 inches and about 0.100 inches. Additionally, it is
envisioned that a distal edge 23 of a distal-most finger 21 is between
about 0.000 inches and about 0.100 inches from a distal-most tip 19 of
leading end segment 18. As can be appreciated, the distances provided
herein are examples and are not intended to be limited to the disclosed
ranges.

[0047] With reference to FIGS. 10-12, alternate embodiments of remote
segment 20 are shown, and are indicated by reference numbers 20a, 20b,
and 20c, respectively. In FIG. 10, remote segment 20a includes three
fingers 21a. As shown, the first transverse dimension "FB" of each
finger 21a is greater than the corresponding first transverse dimension
"SB" of remote segment 20a of leading end segment 18 (i.e., the
portion of leading end segment 20a that finger 21a is in contact with).
Additionally, fingers 21a only extend beyond one lateral edge 25 of
remote segment 20a; fingers 21a are flush with lateral edge 27.

[0049] It is further envisioned that at least one finger 21 and/or remote
segment 20 includes a transverse cross-sectional shape other than the
rectangular cross-sections shown. For instance, finger 21 and/or remote
segment 20 of leading end segment 18 can include any a circular, oval, or
other polygon-shaped transverse cross-section.

[0050] A method of manufacturing a surgical guidewire 10 is also
disclosed. The method includes forming guide member 14 such that guide
wire 14 includes the features as described above. The disclosed methods
include making leading end segment 18 (e.g., remote section 20) and
fingers 21 of the same material (e.g., stainless steel, MP35N® (a
nickel-cobalt alloy), nitinol, or CoCr (a cobalt chromium alloy)), and
include monolithically forming leading end segment 18 according to well
known processes such as die stamping or micromachining (e.g., remote
section 20) and fingers 21. It is also envisioned that leading end
segment 18 and fingers 21 are made of different materials.

[0051] With continued reference to FIGS. 2 and 6-8, leading end segment 18
further includes at least one coil coaxially mounted about at least a
portion of the leading end segment 18, and is mounted within outer sheath
42. In the embodiment, two coils are included, namely, first or proximal
coil segment 44 and second or distal coil segment 46 forward of the
proximal coil segment 44. Proximal coil segment 44 may be fabricated from
a number of suitable materials. Proximal coil segment 44 may be
dimensioned to extend to encompass second annular segment 28 and a
portion of second tapered segment 26. The diameter of the wire of
proximal coil segment 44 may range from about 0.0009 inches to about
0.0025 inches, and, in one embodiment, is about 0.0012 inches. Proximal
coil segment 44 may also have a rectangular or flattened cross-section.

[0052] Distal coil segment 46 extends from proximal coil segment 44 and
encompasses the remainder of leading end segment 18 of guide member 14.
Distal coil segment 46 may be fabricated from a number of suitable
materials, including, for example, stainless steel, MP35N® (a
nickel-cobalt alloy), nitinol, or CoCr (a cobalt chromium alloy). The
wire of distal coil segment 46 has a diameter greater than the wire of
proximal coil segment 44. In one embodiment, the diameter of distal coil
segment 46 ranges from about 0.0012 inches to about 0.0025 inches, and
may be about 0.0015 inches. Distal coil segment 46 may also have a
rectangular or flattened cross-section. The radiopacity of distal coil
segment 46 may assist in placement of leading end segment 18 within the
vasculature through the use of imaging means, e.g., fluoroscopically
during the interventional procedure.

[0053] Proximal coil segment 44 and distal coil segment 46 may provide
lateral and/or torsional support to leading end segment 18. In one
embodiment, the lateral strength (or resistance to bending) of distal
coil segment 46 is less than the lateral strength of proximal coil
segment 44 to permit flexing of a distal portion 38 of leading end
segment 18. The outer diameters of proximal and distal coil segments 44,
46 may approximate each other and may be substantially equivalent to the
diameter of third annular segment 32 to provide a smooth transition. The
configurations of proximal and distal coil segments 44, 46 may be changed
to provide varied properties if desired. In an embodiment, proximal and
distal coil segments 44, 46 may be wound or otherwise disposed about
leading end segment 18 in differing or opposite directions. In
embodiments, adjacent turns of the coils of each of proximal and distal
coil segments 44, 46 are in contacting relation (i.e., they are devoid of
spacing between the adjacent coil turns). In one embodiment, proximal and
distal coil segments 44, 46 may be joined at their interface. In
addition, proximal and distal coil segments 44, 46 may be attached to
leading end segment 18 of guide member 14 along various locations.
Attachment may be effected though the use of adhesives, welding,
soldering or the like. Distal coil segment 46 may be operatively
connected or secured to leading end segment 18 through a soldering
process or with the use of an adhesive such as an epoxy, cyanoacrylate
adhesive or an ultraviolet (UV) light curable adhesive. The soldering or
adhesive element is represented schematically as element 48 in FIG. 3.

[0054] Outer sheath 42 encloses leading end segment 18, and proximal and
distal coil segments 44, 46. Outer sheath 42 may be fabricated from any
suitable material, including, for example, polyurethanes, polyolefins,
polyesters. In one embodiment, outer sheath 42 is a polyurethane sleeve
which may or may not be loaded with tungsten, e.g., in microbead form. If
loaded with tungsten, outer sheath 42 provides an additional element of
radiopacity to leading end segment 18 of guide member 14. Outer sheath 42
may be thermoformed over leading end segment 18, and proximal and distal
coil segments 44, 46 through conventional thermoform techniques. Outer
sheath 42 defines an atraumatic arcuate leading end surface 50 to
minimize the potential of trauma or abrasion of the vessel walls. In one
embodiment, the diameter of outer sheath 42 is less than the diameter of
proximal or trailing end segment 16 of guide member 14 to provide a
smooth transition between the components.

[0055] The Table provided below identifies ranges of dimensions of the
components of the leading end segment 18 for various guidewire sizes in
accordance with the principles of the present disclosure. In the Table, D
is represented as a percentage (%) of the diameter of the trailing end
segment 16 and L represents the specific length of the component. For
example, the diameter of first annular segment 24 may range from about
10% to about 30% of the diameter of trailing end segment 16 and have a
length ranging from about 2 cm to about 10 cm. All ranges are
approximate. Preferred dimensions for the specific guidewire sizes may be
at the midpoint of the specified ranges. Variations of these dimensions
are envisioned.

[0056] It is further envisioned that a lubricious coating may be disposed
over components of guide member 14 including outer sheath 42. Suitable
lubricious coatings include hydrophilic materials such as
polyvinylpyrrolidone (PVP), polyethylene oxide, polyethylene glycol,
cellulosic polymers, and hydrophilic maleic anhydride, or hydrophobic
materials such as silicone, PTFE, or FEP. These coatings are typically
applied by dip coating or spray methods, and heat curing may be used. For
example, cure temperatures up to about 70 degrees C. are used for
silicone coatings, and several hundred degrees may be required for PTFE
coatings. In addition to the lubricious coating, bioactive coatings may
be applied over all or part of the guidewire. Such coatings also may
incorporate materials such as heparin, hirudin and its analogs, or other
drugs. These coatings typically are applied by dip coating. Bioactive
coatings are desirable to prevent blood clotting or for delivery of drugs
to a specific site.

[0057] The above description and the drawings are provided for the purpose
of describing embodiments of the present disclosure and are not intended
to limit the scope of the disclosure in any way. It will be apparent to
those skilled in the art that various modifications and variations can be
made without departing from the spirit or scope of the disclosure. Thus,
it is intended that the present disclosure cover the modifications and
variations of this disclosure provided they come within the scope of the
appended claims and their equivalents.